Individuals who suffer from certain medical conditions are often required to keep an auto-injector or prefilled syringe nearby in order to address a medical need. A few examples of this are insulin pens for people with diabetes, epinephrine for those with food and insect stings allergies, and antidotes for soldiers at risk of exposure to chemical and/or biological toxins in the field. For example, an allergic reaction may occur in a location which is physically distant from the nearest hospital or medical facility. For example, bee stings, are more likely to occur outside than indoors. Food containing peanuts are more likely to be supplied to the individual away from a controlled home environment like at a baseball park. Having a portable epinephrine auto-injector nearby enables emergency intervention after an exposure to an allergen.
Size is an issue when it comes to auto-injectors. Many owners of the devices are hesitant to carry their injector with them if it represents a burden, by providing injectors in more compact sizes it will make it more likely that they will.
Shelf-life is also a large issue with respect to auto-injectors, which can be expensive and used fairly infrequently. For example a user who has intense allergic reactions to shellfish can go years between exposures and subsequent injections. In such a case it can be easy to forget to replace the auto-injector after expiration, whereupon in an emergency, the drugs contained therein have expired and are either ineffective or have a greatly reduced effectiveness due to decomposition of the drugs contained therein. As will be appreciated by those having skill in the art, the shelf life can be increased by storing the desired medication in an unmixed and dry state and dissolved just prior to injection. This ability to store the wet and dry components separately within the device can increase the shelf life and thus increase the likelihood that the user will have an injector with effective dosages when an emergency arises.
In such devices it is required that the mixing and reconstitution processes are consistent and complete prior to injection.